Anatomy 3

Question 1

which muscles do somatic motor nerve fibres stimulate

Answer 1

skeletal muscles

Question 2

how many pairs of spinal nerves are there

Answer 2

31

Question 3

what is a ganglia

Answer 3

a bundle of nerve cell bodies outside CNS

Question 4

how do sympathetic nerve fibres reach the body

Answer 4

within splanchnic nerves: cardiopulmonary and abdominopelvic

Question 5

how do nerve fibres reach the body wall

Answer 5

• sympathetic within the spinal nerves - post synaptic fibres can enter any of the 31 pairs of spinal nerves
• no parasympathetic

Question 6

how do sympathetic nerve fibres reach the head

Answer 6

follow arteries which supply the same structures eg superior, middle and inferior cervical ganglia

Question 7

describe the origin of the spinal nerves

Answer 7

• posterior ramus nerve fibres supplies deep muscles of back, intervertbral joints and overlying skin
• anterior ramus nerve fibres supply most of body - both motor and sensory

Question 8

how do sympathetic nerve fibres get from CNS to kidneys, ureters and bladder

Answer 8

• leave the spinal cord between T10 and L2 and enter the sympathetic chains (bilaterally)
• leave the sympathetic chain in the abdominopelvic splanchnic nerves and synpase at the abdominal sympathetic ganglia which are located around the abdominal aorta
• post synaptic sympathetic nerve fibres pass from the gangllia onto the surface of the arteries which are heading towards the organs they will innervate

Question 9

what is a periarterial plexus

Answer 9

collection of nerve fibres found on the outside of arteries

• sympathetic
• parasympathetic
• visceral afferent

Question 10

which nerves are involved in the parasympathetic system

Answer 10

CN III, VII, X and IX

briefly sacral spinal nerves S2-4

Question 11

how do parasympathetic nerve fibres get from CNS to kidneys, ureters and bladder

Answer 11

• parasympathetic nerve fibres for kidney and ureter are carried in CNX (down to splenic flexure)
• those innervating bladder are carried in pelvic splanchnic nerves

Question 12

pelvic splanchnic nerves

Answer 12

• parasympathetic fibres reach the body structures of hind gut and pelvic organs through these
• carried in sacral spinal nerves briefly

Question 13

Question 14

which parts of the renal system are innervated by somatic motor fibres

Answer 14

those within the perineum eg the urethra (distal to pelvic floor) and its sphincter (external urethral sphincter and levator ani)

Question 15

where is pain from the kidney itself felt

Answer 15

in the loin area - posterior aspect of flank region

Question 16

where is pain felt from a calculus obstructing the ureter

Answer 16

radiate from loin to groin

Question 17

where is pain from the bladder felt

Answer 17

suprapubic region - midline

Question 18

where is pain from the perineal part of the urethra felt

Answer 18

usually quite localised in the perineum

Question 19

how do visceral afferent fibres get from kidneys to CNS

Answer 19

• visceral afferents from the kidneys run alongside sympathetic fibres back to the spinal cord and enter between T11 and L1
• this is why pain is felt in these dermatomes

Question 20

what is the main differential diagnosis of loin pain

Answer 20

muscular pain

Question 21

how do visceral afferent fibres get from ureters to CNS

Answer 21

• run alongside sympathetic nerve fibres and enter spinal cord between T11 and L2
• pain felt anywhere along this path

Question 22

DD of groin pain

Answer 22

hernia

lymphadenopathy

testicular pathology

Question 23

how do visceral afferent fibres get from bladder to CNS

Answer 23

• visceral afferents carrying pain from the superior part of the bladder which touches the peritoneum run alongside sympathetic nerve fibres back to the spinal cord. enter between T11 and L2. pain is percieved in the midline
• visceral afferent fibres from the rest of the bladder that is not touching the peritoneum run alongside parasympathetic fibres back to spinal cord levels S2-4

Question 24

how do visceral afferent and somatic sensory fibres get from urethra to CNS

Answer 24

• visceral afferent fibres from the proximal urethra (above levator ani and in pelvis) run alongside parasympathetic nerve firbes back to spinal cord levels S2-4
• somatic sensory from the remaining urethra are carried within the pudendal nerve back to spinal cord levels S2-4
  
  • pain from this part of the urethra will present as localised pain in the perineum

Question 25

how do pain fibres get from testis to CNS

Answer 25

* testis were embryologically located on posterior abdominal wall * visceral afferents run alongside sympathetic fibres back to spinal cord levels T10-L1 * due to close relationship with scrotal wall, pain from testis can also present localised to scrotum and/or groin (L1 region)

Question 26

how is pain from the distal urethra described

Answer 26

localised and sharp pain in the perineum

Question 27

what reflex happens when the bladder fills

Answer 27

This is a primitive spinal reflex, which is overridden during toilet training * stretch receptors at the end of *visceral afferent* nerve fibres sense this * relay information to CNS via S2-4 (*visceral* *afferents*) * there is a reflex to empty the bladder by stimulation of the detrusor muscle to contract and inhibition of the internal urethral sphincter (in males) (*parasympathetic*)

Question 28

how is the reflex to pee overriden

Answer 28

* the somatic motor nervous system gives us voluntary control - innervates external urethral sphincter and levator ani muscles (pudendal nerves - S2-4) * AP within inhibitory nerve fibres from the cortex pass inferiorly and inhibit this reflex

Question 29

describe the process of micturition

Answer 29

* detrusor muscle contracts - parasympathetic * internal urethral sphincter (males - parasympathetic), external urethral sphincter and levator ani muscles relax (somatic motor - pudendal nerve) * anterolateral abdominal wall muscles contract to increase intra-abdominal pressure and force urine out of external urethral orifice (somatic motor nerve fibres )

Question 30

Answer 30

Question 31

sciatic nerve roots

Answer 31

L4 to S3

Question 32

Answer 32

Question 33

where does the iliohypogastric nerve innervate

Answer 33

comes from lumbar plexus - L1

Question 34

where does the ilioinguinal nerve innervate

Answer 34

comes from lumbar plexus - L 1

Question 35

which nerve arises on the anterior aspect of the psoas major

Answer 35

genitofemoral note lat cutaenous nerve of thigh

Question 36

where does the genitofemoral nerve supply

Answer 36

L1 and L2

Question 37

which nerves arises laterally to psoas major

Answer 37

femoral - L2-4 passes under the inguinal ligament to enter the anterior compartment of the thigh

Question 38

which nerve arises medially to psoas major

Answer 38

obturator (L2-4) goes through obturator foramen in the pelvis to enter the medial compartment of the thigh

Question 39

which compartment of the thigh is the sciatic nerve in?

Answer 39

posterior, enters through via the gluteal region

Question 40

internal urethral sphincter control

Answer 40

* sympathetic stimulate it to contract - occurs during ejaculation * para stimulate to relax - allow urine to flow through urethra

Question 41

Answer 41